Electric heater



Dec. 31, 1935. Q Q ABBOTT 2,026,412

ELECTRI C HEATER Filed June 12, 1934 Inventor: v Charles C. Abbott,

wig/ 89w tcorneg.

Patented Dec. 31, 1935 UNITED STATES PATENT OFFICE.

ELECTRIC HEATER Charles 0. Abbott, Pittsfield, Mass, assignor to GeneralElectric Company,

New York a corporation of Application June 12, 1934, Serial No. 730,221s Claims. (01. 219-19) My inventionrelates to electric heaters and hasfor its object the provision of a simple and compact heater especiallyadapted for use as 9..

one for each length of the resistance conductor,

15 and these wedge members are. secured in place by indentations betweenthem struck in the outer sheath.

For a more complete understanding of my invention reference should behad to the accom- 20 panying drawing in which Fig. 1 is a fragmentaryelevation view partially in section of an electric heating unitembodying my invention; Figs. 2 and 4 are end views of the units shownin Fig. 1; while Fig. 3 is a sectional view along the line 25 3-3 ofFig. 1 looking in the direction of the arrows.

In carrying out my'invention in form I provide an outer metallic sheathor casing l having the desired shape and size of the completed heating 0unit and preferably made of a material having good heating conductivitysuch as copper or brass. As shown, this outer sheath I0 is tubular tinform and has an oval or elliptical cross sec ion. 5 Mounted within theouter sheath I 0 is the electric heating means, shown as a sheathedelectric heating unit of the type described and claimed in my Patent1,494,938, dated May 20, 1924. Briefly stated, this heating unitcomprises a helical resistance heating conductor l I embedded incompacted powdered electrically insulating material l2 in a tubularmetallic sheath 13 which in the present instance may be made of brass orcopper. This sheathed heating unit is bendable, 45 and as shown is bentin the form of a loop or hairpin, there being parallel lengths l4 and 15which fit in the substantially semicircular opposite edges l6 and ll ofthe outer sheath H], as shown in Fig. 3. As shown, the hairpin-shapedresistlength of the outer casing I0 with its terminals l8 and 3|projecting from one end of the casing while the bend (9 of the hairpinis adjacent the other end of the casing.

The parallel lengths I4 and I5 of the sheathed ance heating unitextendssubstantially the'full heating unit are forced outward againstthe inner walls of the casing l0 and wedged in the narrow bends l6 and Hof the casing by means of a plurality of wedgin members placed betweenthem. As shown, the curvature of the bends l6 5 and H is greater thanthe curvature of the sheath l3 whereby this wedging action is providedfor.

These wedging members 20 and 2| are identical in construction with eachother, each being provided with a groove 22 in which lies the adjacent10 parallel length of the heating unit. The members furthermore, asindicated in Figs. 2, 3 and 4, have their side walls 24 and 32 shaped toconform with the oval shape of the outer casing I0. Furthermore eachwedging member is provided at one end with a slot 25 through whichpasses the bend IQ of the heating unit.

These wedging members are forced apart so as to secure the lengths l4and I5 of the heating unit tightly against the inner wall of the outercasing in any suitable manner, as shown by striking a plurality ofindentations 23 in the outer case spaced at intervals along its lengthon each side. It will be observed that the two wedging members havetheir adjacent sides or faces each 25 beveled from its center outward soas to provide two opposite sides 26 and 21 at each side of the casing,as seen in Fig. 3, these sides gradually diverging apart from the centeroutward. Consequently the forcing of the indentations between 30 theseadjacent or opposite sides of the wedging members constitutes aneffective means for forcing the members apart. In this manner thecasing, heating unit and wedging members are rigidly and tightly clampedtogether in good thermal relation with each other. 4

Preferably the heater is assembled by first assembling the sheathedheating unit and wedging members and then inserting these parts in the'outer casing, after which the indentations are 0 formed to secure themtogether. The ends of the casing are closed by plates 28 and 29 which Iare secured in place by punching inward a plurality of tabs 30 in eachend of the casing.

The wedging members 20 and 2| are preferably made of a material havinggood heat conductivity,'such as brass. In addition to their functionofsecuring the heating unit, the wedging members serve to conduct heatfreely from the heating unit to the intermediate regions of the casingIll, i e., the regions between and most remote from the lengths l4 and[5 of the heating unit. It will further be observed that the wedgingmembers, together with the heating unit, almost completely fill thecasing. and

ing is an efiective radiator of heat.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric heater comprising an outer metallic casing having a crosssectional shape providing oppositely disposed relatively narrow curvedportions, a sheathed resistance heating unit shaped in the form of ahairpin and inserted in said casing, said heating unit having a crosssectional curvature less than the curvature of said portions, 9, pair ofwedging members in said casing between the lengths of said heating unitand indentations in said casing between said wedging members forcingsaid wedging members apart against the lengths of said heating unit tothereby force said heating unit into said curved portions of saidcasing.

2. An electric heater comprising an outer metallic casing having a crosssectional shape providing oppositely disposed narrow curved portions, ametal sheathed resistance heating unit in said casing, said heating unitbeing shaped in the form of a hairpin, and having a cross sectionalcurvature less than the curvature of said portions, a pair of heatconducting wedging members in said casing between the lengths tions, apair of wedging members made of heat of said heating unit, said wedgingmembers substantially filling said casing so as to thereby conduct heatto substantially all portions of said casing not in engagement with saidheating unit, and said wedging members having their adjacent faces eachbeveled from the center outward, and indentations in said casing betweensaid wedging members forcing said wedging members apart against thelengths of said heating unit to thereby force said heating unit tightlyagainst said casing.

3. An electric heater comprising an elongated outer metallic casinghaving a cross sectional shape providing oppositely disposed relativelynarrow bent portions, a resistance heating unit extending in a pluralityof lengths in said casing, said unit being provided with a tubularoutermetallic sheath having a cross sectional curvature less than thecurvature of said bent porconducting material between the lengths ofsaid heating unit, said wedging members substantially filling saidcasing so as to thereby conduct heat to substantially all portions ofsaid casing not in engagement with said heating unit, and indentationsin said casing between said wedging" members Vforcing said wedgingmembers apart against the lengths of said heating unit to thereby forcesaid-heating unit into said bent portions;

CHARLES C. ABBO'I'I.

